Is reproduction as “costly” in tropical birds as compared with temperate zone birds?
Why do birds lay so few eggs? Because there is a high cost of reproduction; large reproductive effort now reduces future survival and/or reproduction. This conventional wisdom is based entirely on temperate zone birds that typically lay large clutches. Do tropical birds, which often lay only 2-3 eggs, also face a high cost of reproduction? Brood manipulation studies, the main tool for studying the cost of reproduction, have been performed for only a handful of tropical birds. In most cases pairs cannot raise enlarged broods. In the two species where parental effort was experimentally increased, no effect on future survival was found. Together, these few studies suggest that clutch size in tropical birds may by limited by immediate costs (lack of food) rather than high future costs to survival. The effects of blood parasites on age-related survival in the purple martin (Progne subis): two strikes and you’re out We are undertaking a long term study on the survivorship of purple martins (
